<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <h3>biaoti1</h3>
    <h3>biaoti2</h3>
    <h3>biaoti3</h3>
    <script>
        function add(){
            // console.log(arguments);
            console.log(Array.from(arguments));
            
            
        }
        add(10,20,30);

        let titles = document.querySelectorAll("h3");
        // console.log(titles);
        console.log(Array.from(titles));
        

        var user = {
            "0":"liwancai",
            "1":20,
            "2":"nan",
            length:3
        }
        // console.log(user);
        console.log(Array.from(user));
        
        
        
    </script>
</body>
</html>